Process for producing amorphous copolymerizates of ethylene and higher alpha-olefin



United States Patent Claims: c1. 26088.2)

This application is a continuation of application Ser. No. 260,835,filed Feb. 25, 1963, and now abandoned.

This invention relates to a process for the preparation of linear,amorphous, high molecular weight copolymers of ethylene and one or morehigher alpha-olefins. More particularly, this invention relates to aprocess for the preparation of such ethylene-propylene orethylene-butene-l copolymers.

In summary, this invention provides a process for copolymerizingethylene and a higher alpha-olefin in contact with a catalyst theessential starting components of which are a dialkyl aluminum halide anda coordination compound of a Lewis base with a halogenated vanadiumcompound.

Until recent times, the known copolymerizates of ethylene with a higheralpha-olefin, such as propylene, were film-forming plastic materialsmade up of macromolecules each exhibiting a partial crystallinity at theX-rays.

Elastomeric high molecular weight copolymerizates of 1 ethylene and,e.g., propylene which are amorphous when examined under the X-rays, andfree or substantially free of homopolymers of the respective monomers,have been disclosed only recently, and as is known, have been obtainedonly by the use of a comparatively few selected and particular catalystsystems.

The present invention provides an improved process according to whichthere is obtained a marked increase in the copolymerization rate and inthe yield of copolymer based on the amount of catalyst used.

According to the present invention ethylene and one or more higheralpha-olefins are copolymerized in the presence of a catalyst preparedby mixing a dialkyl aluminum halide with a coordination compound of aLewis base with a halogenated vanadium compound, the catalystpreparation and the copolymerization being carried out at a temperatureof from 0 C. to -180 C, preferably from 10 C. to 50 C.

The preferred dialkyl aluminum halides R R AlX, used in preparing thecatalyst are those in which each of the alkyl radicals R and Rpreferably contains from 1 to 6 carbon atoms, and in which X is anyhalogen, specifically chlorine or fluorine.

Typical halogenated vanadium compounds which form coordination compoundswith a Lewis base that are useful as one catalyst-forming componentinclude vanadium tetrachloride, vanadium trichloride, and vanadyltrichloride.

Lewis bases which form coordination compounds with the halogenatedvanadium compound include e.g.

(a) aliphatic ethers, such as diethyl ether, dipropyl ether anddiisobutyl ether; diethoxy ethane, etc.;

(b) cyclic ethers, such as tetrahydrofurane, dioxane, etc.,

(c) tertiary amines, such as trimethyl amine, diethyl methylamine, etc.,

3,369,011 Patented Feb. 13, 1968 (d) heterocyclic nitrogen bases, suchas pyridine, quincline, etc.

The catalyst may be preformed by dissolving the dialkyl aluminum halidein a solvent, and mixing the resulting solution with a solution of thevanadium compound-Lewis base coordination compound, the mixture beingthen brought into contact with the monomers to be copolymerized.

In a presently preferred embodiment, however, the catalyst is preparedin the presence of the monomers to be copolymerized.

The activity of the catalysts prepared and used at the temperature inthe range 0 C. to 80 C. is much higher than the activity of the samecatalysts prepared at higher temperatures and, moreover, the activity ofthe catalysts prepared and used at 0 C. to 80 C. remains practicallyconstant.

The activity of the present catalysts varies with the molar ratio of thecatalyst-forming components. Advantageously, the molar ratio of dialkylaluminum halide to vanadium compound-Lewis base coordination .compoundis from 2:1 to 30:1, preferably from 4:1 to 20:1.

The copolymerization of ethylene and the higher alphaolefin can becarried out in the absence of a solvent, or in an inert hydrocarbonsolvent which can be an aliphatic hydrocarbon such as, for example,n-heptane or isooctane; an aromatic solvent of which benzene and tolueneare exemplary; or a halogenated hydrocarbon such as chloroforrrr,trichloroethylene, tetrachloroethylene, chlorobenzene, etc. or mixturesthereof.

Ethylene and the other alpha-olefin can be copolymerized with thepresent catalyst in a continuous process, by feeding additional catalystto the system as required, either periodically or continuously, duringthe copolymerization; by maintaining constant the ratio between themonomers concentration in the liquid phase by feeding continuously intothe system a mixture of the monomers having a constant composition.

If the continuous copolymerization is carried out in the absence of theextraneous inert solvent, a monomers mixture comprising a minor amountof ethylene and a major amount of propylene (or other higheralpha-olefin) may be fed continuously into the system while maintainingconstant temperature and pressure conditions.

The ethylene/ higher alpha-olefin copolymerizates, more particularly theethylene/propylene and ethylene/butene-l copolymerizates obtained by thepresent process and which contain ethylene in an amount below by moles(e.g., between 5% and 75 by moles) are completely amorphous whenexamined under the X-rays.

Such copolymerizates are obtained by maintaining a fixed molar ratio ofthe monomers in the mixture to be copolymerized, throughout thecopolymerization.

Ethylene and propylene can be copolymerized to an amorphouscopolymerizate by maintaining a propylene to ethylene molar ratio of 4:1or higher in the liquid phase throughout the copolymerization, molarratios of 200:1 to 4:1 being satisfactory.

Ethylene and butene-l can be copolymerized to an amorphouscopolymerizate by maintaining a butene-l to ethylene molar ratio of 20:1or higher in the reacting liquid phase, molar ratios of 1000:1 to 20:1being satisfactory.

Taking the foregoing into account, it is possible to obtaincopolymerizates of widely varying composition by varying the mol ratioof the monomers present in the liquid phase.

The copolymerizates are solid at normal temperature and usually have amolecular weight in excess of 20,000, as determined from the intrinsicviscosity.

The amorphous copolymers obtained by the present process are useful inthe synthetic rubbers arts; they are 5 vulcanizable and when vulcanizedyield elastomers having good mechanical properties.

The following examples are given to further illustrate the invention andare not intended as restrictive:

Example 1 The reaction apparatus consists of a large glass tube of 750cc. capacity, a 5.5 cm. diameter, provided with tubing for gas inlet andoutlet, a mechanical stirrer and a thermometer casing, The gas inlettube extends down to the bottom of the container and ends in a porousdisk having a diameter of 3.5 cm. The apparatus is thermostatically setat a temperature of C. '350 cc. .of anhydrous n-heptane are introduced,and this solvent is then saturated at a temperature of 20 C. by feedingin a mixture containing propylene and ethylene in 4:1 molar ratio, at arate of 250 Nl./h.

Meanwhile the catalyst is prepared at a temperature of 20 C. by mixing14 millimols of diethyl aluminum monochloride in 20 cc. anhydroustoluene with 2.8 millimols of vanadium trichloride tetrahydrofuranate in20 cc. anhydrous toluene.

The catalyst thus prepared is introduced into the reaction apparatus oneminute after it is prepared. The feeding of the propylene/ ethylenemixture is continued at a rate of 400 Nl./h. Ten minutes after thecatalyst is introduced, 20 cc. of methanol are added to stop thereaction.

The resulting product is freed of inorganic impurities by subjecting it,repeatedly, to treatment with aqueous hydrochloric acid, and separatingthe two phases which are formed.

The heptane phase. is then washed with water until it becomes neutral,and the copolymer is coagulated by treating it with an excess of anacetone-methanol mixture, and dried in vacuo.

The vacuum-dried product amounts to 15 g. of a white and rubberlikesolid which is completely amorphous at the X-rays.

It contains about 40% mols of ethylene, as determined by a radiochemicaltest, and has an intrinsic viscosity, determined in tetralin at 135 (3.,equal to 2.4.

The average copolymerization rate is of 296 g. copolymer Xliter g.vanadium Xh. X mole (CgH4-i CQHB) 5 5 g. copolymerXliter g. vanadiumX h.X mole (C H C H Example 2 Example 1 is repeated, except that V01pyridinate is used for the preparation of the catalyst, in place of VCltetrahydrofuranate. 75

Into the reaction apparatus as described in Example 1, previouslydeaerated and thermostatically seat at 20 C., 350 cc. n-heptane areintroduced under nitrogen, and this solvent is then saturated by feedingin a gaseous mixture of propylene-ethylene in 4:1 molar ratio, at a rateof 200 NL/h.

Meanwhile, the catalyst is prepared at a temperature of 20 C. by mixing1.4 millimols of tripyridinate of vanadium trichloride (VCl .[C H N]3)in 25 cc. of anhydrous toluene with 7 millimols of diethyl aluminummonochloride in 25 cc. of anhydrous toluene.

One minute after it is prepared, the catalyst is siphoned under nitrogeninto the reaction apparatus.

The feeding of the propylene/ethylene mixture is continued for 10minutes, at a rate of 400 Nl./h., While stirring.

30 cc. methanol are introduced to stop the reaction, and the copolymerobtained is purified by treating it repeatedly with aqueous hydrochloricacid. It is coagulated eventually with acetone and methanol. 4 g. of anethylenepropylene copolymer are obtained which contains about 48% molsof ethylene. The copolymer is completely amorphous at the X-rays. Theaverage oopolymerization rate is of 159 g. copolymer liter g. vanadium Xh. X mole (C H l- C ll Operating under the same conditions, but carryingout both the catalyst preparation and the copolymerization at atemperature of 25 0., instead of at 20 C., there are obtained only 0.3g. of ethylene-propylene coploymer in 25 minutes, which corresponds toan average copolymerization rate of g. copolymerXliter g.vanadiumXhXmole (C H +C;,H

Example 3 Into the reaction apparatus as described in Example 1, whichis thermostatically set at 20 C., there are introduced 350 cc. ofanhydrous n-heptane, which is then saturated, at a temperature of 20 C.by feeding in, a propylene-ethylene mixture at a rate of 250 Nl./h.

The catalyst is prepared under nitrogen at a temperature of 20 C., bymixing 14 millimols of diethyl aluminum monochloride in 20 cc. ofanhydrous toluene with 2.8 millimols of the complex formed by vanadiumtrichloride with symmetrical diethoxyethane in 20 cc. of anhydroustoluene.

The catalyst thus prepared is introduced into the apparatus one minuteafter it is prepared. The feeding of the ethylene/ propylene mixture iscontinued at a rate of 400 NL/h. 20 minutes after the introduction ofthe catalyst, the reaction is stopped by adding 20 cc. methanol. Theproduct is purified and separated as described in Example 1. Aftervacuum drying, 20 g. of a white and rubber-like solid, amorphous at theX-rays, are obtained.

It contains 45% mols of ethylene, as determined by radiochemical test.

The average copolymerization rate is of 172 g. copolymerXliter g.vanadiumXh. mole (C H +C H g. copolymerXliter g. vanadiumXh. Xmole (CH.1+ a o) Example 4 A 6 liter autoclave, provided with a stirrer and ajacket for the circulation of a cooling fluid, is charged with 4 litersof liquid propylene at 10 C., which is then satuhub rated toequilibrium'with ethylene under a total pressure of 5 abs. atm.

1.24 g. of vanadium trichloride tr-ipy-ridinate (3.2 mols) and 4.64 g.of diethyl alumium monochloride (38.5 mols) are then introduced.

The copolymerization is carried. out at C. for 1 /2 hours, while thepressure is maintained constant by a continuous feed of ethylene, inorder to maintain the composition of the liquid phase constant at 97% bymol of propylene. When the reaction is completed, 495 g. of copolymerare obtained which is amorphous at the X-rays with a yield of 1000 g./g. of vanadium trichloride. The dried product has the followingcharacteristics:

Viscosity Mooney ML 1+4 at 100 c 100 Temperature of minmum elasticrebound C 38 Carbon Black HAF Kosmos 60 50 Dicumyl peroxide 2 Sulfur0.24

and the mixture was vulcanized by heating it in a press at 165 C. for 30minutes. The vulcanizate has the following characteristics:

Ultimate tensile stress, l g./cm. 241 Elongation at tensile breakingpoint, percent 475 Elastic modulus at 300%, kg./cm. 113 Permanent setafter breaking, percent 6.5

Resistance to tearing,-kg./cm. 42

Example 5 350 cc. of anhydrous n-heptane are introduced into the samereaction apparatus, thermostatically set at 20 C., which was describedin Example 1. A gaseous mixture of propylene-ethylene in a molar ratio4:1 is fed through the gas inlet line, and circulated at a rate of 200Nl./h. The catalyst is pre-formed in a 100 cc. flask by reacting in 30cc. of anhydrous toluene at 20 C. under nitrogen, 1 millimol of vanadiumtetrachloride bipyridin-ate and 5 mi-llimols of diethyl aluminummonochloride. The catalyst thus prepared is held at 20 C. for one minuteand then siphoned into the reactor by means of nitrogen pressure.Circulation of the ethylene-propylene mixture is continued at a rate of400 Nl./h. After 10 minutes from the introduction of the catalyst, thereaction is stopped by adding methanol. The product is purified andrecovered as described in Example 1.

After vacuum drying, 4 g. of a solid product, amorphous at the X-rays,completely soluble in boiling n-heptane and having the appearance of anunvulcanized elastomer, are obtained.

The average copolymerization rate corresponds to 2 g. oopolymerXliter g.vanadiumXh. Xmols (C H +C H Operating under the same conditions, butpreparing the catalyst and carrying out the polymerization at 25 C.,instead of at 20 C., there is obtained only 1 g. of anethylene-propylene copolymer in 20 minutes, which corresponds to anaverage rate of 8 g. copolymer liter g. vanadium X h. mols (0 ,11 C HExample 6 mols of diethyl aluminum monochloride. The catalyst is held at20 C. for one minute and then siphoned into the reactor by means ofnitrogen pressure. Feed and discharge of the ethylene-propylene mixtureare continued at a rate of 400 Nl./h.

After 8 minutes from the start, the reaction is stopped by addingmethanol. The product is purified and recovered as described in Example1.

After vacuum drying 5 gare obtained of a solid product, amorphous at theX-rays, completely soluble in boiling n-heptane, and having theappearance of an unvulcanized elastomer.

The copolymerization rate corresponds to g. copolymerXliter 277 g.vanadium X h. Xmols (C H -i- C 11 By operating under the sameconditions, but preparing the catalyst and carrying out thepolymerization at 25 C., instead of at 20 C., only 1.1 g. of anethylene-propylene copolymer is obtained in 20 minutes, whichcorresponds to g. copolymer liter 108 g. vanadiumXh. mols (C H +C Htrimethyl amine diethyl methylamine diisobutyl ether pyridine oxidediethoxy ethane pyridine, and tetrahydrofuran quinoline dioxane at amolar ratio of (A) to (B) in the range 2:1 to 30:1,

and at a molar ratio of higher alpha-olefin to ethylene in I the liquidphase of at least 4:1 when the higher alphaolefin is propylene, and ofat least 20:1 when the higher alpha-olefin is butene-l, which process ischaracterized in that both the preparation of the catalyst and thecopolymerization are carried out at a temperature in the range 0 C. toC., where there is obtained a yield of the amorphous copolymerizate perunit weight of catalyst used higher than is obtained when the catalystis prepared and the copolymerization is carried out at temperaturesabove 0 C.

2. The process according to claim 1, further characterized in that boththe preparation of the catalyst and the copolymerization are carried outat a temperature in the range of from 10 C. to 50 C.

3. The process according to claim 2, further characterized in that themixed monomers are copolymerized in an inert solvent selected from thegroup consisting of aliphatic, aromatic and halogenated hydrocarbonsolvents.

4. The process according to claim 2, further characterized in that themixed monomers are copolymerized in the liquid phase in the absence ofan extraneous solvent.

5. The process according to claim 2, further characterized in that thecomonomers are ethylene and liquid propylene.

6. The process according to claim 2, further characterized in that thecatalyst is obtained by mixing (A) diethyl aluminum monohalide and (B)vanadium trichloride tetrahydrofuranate.

7. The process according to claim 2, further characterized in that thecatalyst is obtained by mixing (A) 7 diethyl aluminum monohalide with(B) vanadium trichloride pyridinate.

8. The process according to claim 2,. further characterized in that thecatalyst is obtained by mixing (A) diethyl aluminum monohalide with (B)a complex formed of vanadium trichloride and symmetrical diethoxyethane.

9. The process according to claim 2,. further characterized in that thecatalyst is obtained by mixing (A) diethyl aluminum monohalide and (B)vanadium tetrachloride bipyridinate.

10. The process according to claim 2, further characterized in that thecatalyst is obtained by mixing (A) diethyl aluminum monohalide and (B) acomplex of vanadium trichloride and pyridine oxide.

References Cited UNITED STATES PATENTS 2,996,459 8/1961 Andersen et a1.260-882 3,116,274 12/1963 Boehm et al. 26094.9 3,139,418 6/1964 Marulloet a1 260-93.7 3,205,216 9/ 1965 McManimie 26094.9

FOREIGN PATENTS 564,772 8/ 1958 Belgium. 851,113 10/1960 Great Britain.

JOSEPH L. SCHOFER, Primary Examiner.

M. B. KURTZMAN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,369,011 February 13, 1968 Alberto Valvassori et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

in the heading to the printed specification, line 6, for "Guido Sartoni"read Guido Sartori Signed and sealed this 1st day of April 1969.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

1. THE PROCESS FOR PRODUCING SOLID, LINEAR, AMORPHOUS COPOLYMERIZATES OFETHYLENE AND A HIGHER ALPHA-OLEFIN SELECTED FROM THE GROUP CONSISTING OFPROPYLENE AND BUTENE-1 BY COPOLYMERIZING A MIXTURE OF THE MONOMERS, INTHE LIQUID PHASE, IN CONTACT WITH A CATALYST OBTAINED BY MIXING (A) ADIALKYL ALUMINUM HALIDE IN WHICH THE ALKYL GROUPS EACH CONTAIN FROM 1 TO6 CARBON ATOMS AND (B) A COORDINATION COMPOUND OF A HALOGENATED VANADIUMCOMPOUND AND A LEWIS BASE SELECTED FROM THE GROUP CONSISTING OF